Engineer acknowledges removing probes after reservoir collapse

JEFFERSON CITY, Mo. -- An Ameren Corp. engineer said Wednesday a manager told him to remove critical safety probes from their casing at the Taum Sauk reservoir and test them just hours after the structure collapsed.

"We wanted to find out what happened -- why the thing didn't work," Tom Pierie said during sworn testimony at a Public Service Commission inquiry into one of the worst man-made disasters in Missouri history.

The safety probes have become a key focus of the commission's investigation into the reservoir collapse. A Missouri State Highway Patrol investigation revealed that Ameren employees or contractors adjusted the probes so the reservoir could run at full capacity. By the time of the collapse, the probes had effectively been disabled.

The commission heard testimony last week from Missouri's top dam safety official, who said the probes should not have been removed immediately after the reservoir collapse.

Now officials might never know if the probes were properly set the morning of the accident, said James Alexander, Missouri Department of Natural Resources dam safety chief.

Pierie challenged that assessment during his testimony Wednesday. He said that although he and an Ameren manager removed the probes, they left in place cables that were clearly marked with electrical tape so officials could tell where the probes had been set.

It remains unclear who moved the probes to an unsafe level prior to the collapse. Pierie and the contractor he hired to install the probes -- Tony Zamberlan -- both have denied doing it.

But Pierie said he removed the probes from their case at the direction James Witges, whom Pierie identified as supervisory engineer at Ameren.

The so-called Warrick probes were set along the top of the reservoir wall. If water ever touched the probes, they were designed to shut down automatic pumps that filled the reservoir so the giant basin would not overflow.

Pierie echoed earlier testimony when he said the probes had been raised so high that water never touched them the morning of Dec. 14, 2005, when the basin overflowed and caused a huge portion of the earthen wall to give way.

The resulting flood devastated Johnson's Shut-Ins State Park and injured a family of five. Attorney General Jay Nixon said he will not file criminal charges in the case, though he is suing the utility company.

Federal criminal investigators with the Environmental Protection Agency are investigating the accident.

PSC Comissioner Steve Gaw said the hearing was shedding new light on safety procedures at Ameren, which operates several power plants in eastern Missouri and Illinois. Gaw indicated he was especially concerned with Pierie's testimony that Ameren employees and contractors adjusted the Warrick probes without leaving any record of their actions.

"It appears there weren't any written protocols," Gaw said.

Pierie said that in 2004 he helped design and install the automatic control system that drained and filled the Taum Sauk reservoir -- including the Warrick probes.

He said he drove down to the hydroelectric plant just hours after the collapse, and couldn't understand why the probes never sounded an alarm when water poured over the walls.

The probes worked by sending out an electrical current when they touched water. Pierie said he and Ameren employee Robert Scott pulled the probes from their casing and "shorted" them out against a metal box to ensure they worked. They did.

He said he returned downhill to the Taum Sauk power plant after the brief test. That's when Witges told him to remove the probes and put them in water to test them -- which would more realistically create conditions in the reservoir.

Pierie said he, Witges and another Ameren engineer removed the probes from their casing and tested them in water before any state or federal investigators arrived.

They coiled up wires attached to the probes and left them at the top of the reservoir. He said it would be easy to later figure out at what level they had been set before because of pieces of tape on the wires.

"It was pretty evident where these probes were at," Pierie said.

Pierie was the only witness to testify Wednesday. The PSC plans to call a former Taum Sauk plant manager and an Ameren executive to testify Thursday.